1. create a for
2. bound the form to the table you created
Select * From MyTable Where customerId=forms![FormName]![CustomerID] (see
part four)
3. create all the fields in the form, bound the text boxes to the fields
from the table.
4. create another field, unbounded, where the user can enter the customerID
5. on the after update event of the customerid (4), enter the code

IF isnull(dlookup("CustomerID","MyTable", "CustomerID = " & me.customerID))
then
   msgbox "Customer does not exist"
else
   me.requery
end if

I hope it will work up